This invention relates to an assembly of a rimless spectacle frame and a spectacle lens, and more particularly to an apparatus and method for retaining a spectacle lens on a rimless spectacle frame with a tough cord.
FIG. 1 shows a pair of conventional sunglasses provided with a rimless spectacle frame 1. In this figure, a spectacle lens 2 is removed from the frame 1. The frame 1 has two inverted U-shaped portions which are interconnected. Each of the inverted U-shaped portions is formed in its inward surface with an open-ended lens receiving slot in the same manner as that of ordinary spectacle frames so as to engage with the upper peripheral portion of a lens 2. The peripheral surface of the lens 2 has an annular slot 21. Each end portion of each inverted U-shaped portion is formed with two parallel through holes 11. Bridging two end portions of each inverted U-shaped portion is a tough cord 3 which is made of cattle tendon or the like. After each end portion of the cord 3 has been passed through two adjacent through holes 11 in each end portion of the inverted U-shaped portion, it is knotted. Then, the cord 3 is pulled downwardly permitting the lens 2 to be inserted into the lens receiving slot in the frame 1. Finally, the cord 3 is brought into engagement with the annular slot 21 thereby retaining the lens 2 on the frame 1. When the distal ends of the cord 3 are exposed to the exterior of the frame 1, they are cut off with a pair of scissors.
Because the cord 3 must be knotted, the time required to fasten the lenses 2 onto the frame 1 is largely increased. Furthermore, Because the knotting step is conducted by hand, the length of the cord 3 is not fixed. When the length of the cord 3 is excessive, it is difficult to retain firmly the lens 2 on the frame 1. Or, when the cord 3 has an insufficient length, it easily suffers from resilience fatigue. To insure the quality of the product, an improvement in the assembly of the rimless spectacle frame, spectacle lens, and the tough cord is required.